Hydraulic operating circuit for machine tools and the like



I Dec. 9, 1947. GE|GER 2,432,305

HYDRAULIC OPERATING CIRCUIT FOR MACHINE TOOLS AND THE LIKE Filed March a. 194

INVENTOR GEORGE M. semen.

ATTORNEY5 trolled.

UNITED STATES PATENT OFFICE .nrnmlmc ornm'rmc cmcurr roa I momma TOOLS AND THE LIKE I George M. Geiger, Mount Gilead, Ohio, assignor to H-P-M Development Corporation, Wilmington, Del., a corporation of Delaware Application, March 6, 1944, Serial No. 525,257

3 Claims.

1 This invention relates to fluid operable systems and,- in particular, to fluid operable systems wherein it is desired to control the speed of move- .ment of a drivenelement.

In many hydraulic applications, such as machine tools, it is desired to control the speed of a rotary or a reciprocating element in order to improve the operating characteristics of the machine. Accordingly,:it is a primary object of this invention to provide a hydraulic circuit including a motor wherein the speed of the motor is con- It is another object of this invention to provide, insuchYa /circuit, a means for adjustin General arrangement According to this invention, a fluid operable motor, which may be of either the rotary or reciprocating type, is supplied with pressure fluid from a source of variable delivery, which latter includes means for controlling the flow therefrom.

Valve means is provided for by-passing the deliveryof said fluid source when the driven motor is idle. Other valve means are provided or directing the delivery of the said pump to the motor and is operable tocause the said motor to move in a. forward or in a reverse direction.

The discharge of the motor is passed through a throttling valve thereby to generate a pressure on the inlet side of the said valve. This pressure, in

.2 I I the motor I a pump III is provided which draws fluid through a conduit I I from areservoir I2 and expels the same at increased pressure into a conduit I3. 7

The conduit I3 is connected by a branch conduit I4 with the port 1 in the cylinder 2, and by a conduit I5 with the inlet port of a-3-way valve I8.

The 3-way valve Iicomprises a casing I1within which is reciprocably mounted a valve member I8 which isadapted to be reciprocated within the said valve casing by a pair of pilot plunger-s l9 and 20. The pilot plungers Ifi'and are reciprocably mounted in the pilot cylinders 2| and '22 which are suitably secured to .the'opposite ends of the casing I1.

The valve I6 is connected to the port 8 in the 4 cylinder 2 by a conduit and by the conduits combination with a suitable yielding means, is effective to actuate the flow controlling device associated with the fluid source.

Detailed description Referring now to the drawing more in detail,

I there is shown a fluid operable motor I which comprises a pressure casing 2 having mounted therein a movable work member 3. Ifthe fluid operable motor I is of the reciprocating type, as shown, the work member 3 comprises a piston 4 and a ram 5 reciprocably mounted within the 26 with the inlet of an adjustable choke or throttling valve 21, which latter has its outlet in continuous fluid communication with the reservoir tween the conduits I5 and 25 and, in its left hand position, to establish fluid connection between conduits 25am]. 26.

Also branching off from the conduit I3is a conduit 30 which leads to a 2-way valve 3|. The 2- way valve 31 also comprises a movable valve member 32 which is selectively movable into position to eifect' fluid connection between conduit 30 and the conduit 3I leading to'the reservoir I2 and into positionto interrupt the said fluid connection. The valve 3| may beoperated in any convenient manner such as the manual means shown in the-drawing and is for the purpose of freely by-passing the pump delivery in order to cause the motor I to idle.

A relief valve 33 is included in a conduit 34 which leads from the conduit I3 to the reservoir I2. The function of the relief valve is to relieve excessive pressures within the conduit I3 during the operation of the hydraulic system.

The pilot cylinders 2| and 22 of the valve I6 are connected by the conduits 35 and 36 respectively with the 4-way pilot valve 31. Pressure 1 fluid is supplied to the pilot valve 31 through a conduit 38 fromany suitable pressure fluid source such as the auxiliary pump 39. The pump 39 may be of any type such asa gear pump and may be by-passed by a relief valve such as at 40 in order to by-pass excessive delivery therefrom. The 4-way pilot valve 31 also has connected thereto the exhaust conduit H which leads directly to the reservoir l2 and serves as a channelv to Suitably attached to the ram 5 is anrarm 45 which carries a rod 46 which has attached thereto the collars 41 and 48. The collars 41 and 48 are positioned so as to engage the arms of the lever 43 to move the same and thereby to shift the valve rotor 42. The arrangement is such that, when the ram 5 completes its travel in either direction and-engages the lever 43 and shifts the same, the fluid connection established withinthe valve 31 and will be such that the valve l6 will be shifted into position to reverse the travel of the said ram.

Also associated with the pilot valve 31 is a reciprocating fluid motor 50 which is provided for the purpose of feeding the work or tools toward one another during the operation of the machine which is to be driven by the hydraulic circuit of this invention. The motor 50 is provided with opposed areas, one of which is connected with the conduit 35 and the other of which ls'connected with the conduit 36. Since one of the said conduits is always under pressure while the other is being exhausted, the motor 50 is moved first in one direction and then in the other Y as the valve member 42 of the valve 31 is moved noted that the actuation of the motor 50 occurs at the instant of reversal of the motor Referring more particularly to the pump II], this will be seen to comprise a variable delivery pump having a movable flow control member to which is attached a yielding mean urging it towards maximum delivery position and a fluid operable means arranged in opposition to the said yielding means. The yielding means is contained within the cylinder 60 and comprises a spring 6| which bears against the head 62 of a rod 63 which is attached to the pump flow control memher. The thrust of the spring BI is adjusted by means of an adjusting member 65 which may be, as shown, a rod threadedly engaging the end wall ofthe cylinder 50. Arranged on the opp e S de of the pump is a cylinder 10 within which is reciprocably mounted a piston 1| attached to a piston rod 12 which latter abuts or is connected with the said flow control member of the pump Ill. Fluid pressure is'introduced into the cylinden 10 through a conduit 13 which leads from ghe said cylinder to the inlet of the choke valve Operation In operation the pumps l0 and 39 are driven from any suitable source such as individual motors or a single motor and the ram 5 is caused to reciprocate in the following manner: assume that the motor is standing idle with the delivery of the pumpv l0 being by-passed through the conduits I3, 30 and 3|. A working stroke of the ram 5 is instituted by moving the valve member 32 to the right thereby to close off the aforementioned by-pass connection. If the valve memberll of the valve I6 occupies the position shown in the drawing then the delivery of the pump I6 is directed through the conduits l3 and IE to the valve I6 and thence through the conduit 25 to the right side of the piston 4. Pressure also stands through the conduits l3 and I4 to the cylinder 2 and on the left side of the piston 4. The right side of the piston 4, being the larger, will cause the piston 4 of the ram 5 to move leftwardly and at a relatively high rate of speed.

When the leftward movement has progressed to the point where the collar 48 engages the lever 43 and shifts the same counter-clockwise, the valve member 42 is likewise shifted counterclockwise and fluid connection between the conduits 38 and 35 and between the conduits 36 and 4| is established. The first of these connections is effective to cause pressure from the pilot pump 39 to be delivered to the pilot cylinder 2| and, through the plunger Hi, to move the valve member I8 into its lefthand position. At this time, the fluid within the pilot cylinder 22 is exhausted to the conduit 36, the valve 31 and the conduit 4| to the reservoir.

The shifting of the valve member IE to the left cuts off fluid communication between the conduits I5 and 25 and establishes fluid communication between the conduits25 and 26.

The right hand side of the piston 4 now being exhausted, while the left hand side remains under pressure, the piston and ram will move to the right, with the full delivery of the pump passing through the conduits I3 and I4 into the cylinder 2 to the left of the piston 4.

The rightward or working movement of the ram 5 is accomplished at a controlled rate of speed by controlling the delivery from the pump in accordance with the pressure created at the inlet of the choke 21 by the passage therethrough of the exhaust fluid from -the cylinder 2. It will be noted that, when the ram 5 is performing its working or rightward stroke, the entire discharge from the right end of the cylinder .2 is conducted through the conduits 25 and 26 to the inlet of the flow responsive means or choke 21 and therethrough to the reservoir l2. The pressure created at the inlet of the said flow responsive means is, in accordance with well known hydraulic laws, in directproportion to the rate of fluid flow through the said means. Thus, the pressure created at the inlet of the choke valve 21 and, therefore, in

the conduit 13, is directly proportional to the speed at which the ram 5 moves during its working stroke. Also the thrust on the piston 1| created by the pressure conducted thereto by the conduit 13 is proportional to the rate of travel of the ram 5 and is effective to urgethe flow control member of the pump Ill toward reduced delivery position until the latter occupies such a position that the rate of delivery of fluid from the pump to the motor causes the motor to travel at a speed in accordance with the setting of the choke 21 and the spring adjusting means '65. That is, the speed of the motor will be such that the rate of fluid exhaust therefrom will create a pressure at the inlet of the choke 21 and,- therefore, a thrust on the piston 1| which is exactly equal to the thrust of the spring 6 l.

It will be apparent that the speed of the workeration with the fluid operable means 10, 1| and the yielding means BI is effective automatically to maintain the speed of the ram 5 at any predetermined value.

Inasmuch as various modifications and substitution of equivalents or alterations in structural arrangements may be made without departing from the spirit of this invention, it will be understood that I do not wish to be limited to the specific structure shown and described, but desire to comprehend such modifications as come within the spirit of the claims.

Having thus fully described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a hydraulic system; a reciprocable ram having associated therewith an advancing area and a larger retraction area; a variable delivery pump in continuous hydraulic communication with said advancing area and including a movable flOlV control member; a valve means having a first port connected with said pump, a second port connected with said retraction area, and including a third port; a choke valve having its outlet connected to exhaust and its inlet connected to said third port; said valve being movable selectively to interconnect said retraction area with said pump or with the inlet of said choke valve; opposed fluid operable plungers associated with said valve for moving the same from one position to the other; a source of pilot fluid for supplying actuating fluid to said plungers; a rotary pilot valve for controlling the supply of fluid from said source to said plungers and adapted, in response to a predetermined movement of said ram in either direction, to be engaged and moved thereby to vary the supply of pilot'fluid to said plungers thereby to cause the same to move said first mentioned valve into position to bring about the reversal of said ram; said pump flow control member having associated therewith yielding means continuously urging the same toward increased delivery position and a fluid operable plunger hydraulically connected with the inlet of operable for bypassing the entire delivery of said pump.

2. In a hydraulic circuit for a machine tool moving the same into its positions; a pilotpump; a rotary-valve interconnecting said pilot pump with said fluid pressure responsive actuating means and movable to direct fluid to one or the other thereof; said second motor being connected in parallel with said fluid pressure responsive actuating means for receiving fluid from said pilot pump when said rotary valve is shifted.

3. In a hydraulic circuit for a machine tool having a work table and a work or too-l feed; a differential plunger connected with said table; a fluid operable motor for actuating said feed; a fluid source of variable delivery; a reversing valve interconnecting said source with said plunger and movable into a first position to direct fluid to both sides of said plunger and into a second position to exhaust the larger end of said plunger; 2, pair of opposed fluid operable means for actuating said reversible valve; a pilot pump for supplying actuating fluid to said fluid operable means; a rotary pilot valve adapted for actuation by. said plunger at the opposite ends of its stroke alternately to direct fluid from said pump to said pair of fluid operable means while the other of said pair is exhausting; said fluid operable motor also being connected to receive fluid from said rotary pilot valve thereby to be actuhaving a reciprocable work table and a work or reversing valve connecting said pump with, said.

first motor and movable for supplying fluid to said motor in both directions of movement thereof; a pair of fluid pressure responsive actuating means associated with said reversing valve for ated at opposite ends of the stroke of said plunger; and means operable when said reversing valve is positioned to direct fluid to the smaller area of said plunger and to exhaust thelarger area thereof for maintaining the delivery of said source substantially constant to. maintain the speed of said plunger substantially constant.

- GEORGE M. GEIGER.

REFERENCES CITED The following references are of record in the file of this patent:

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